The fact that M/3 is not an integer means that M is not divisible by 3. Thus, we should start from the highest 2-digit number and go back to find the highest possible value of N.- N=99 -> it's divisible by 3- N=98 -> not divisible by 3 but N would be 51.5 that is not an integer- N=97 -> not divisible by 3 and N would be 51. The highest value of N is 51!